USB2514B-AEZC-TR Datasheet, PDF (8/63 Pages) SMSC Corporation – USB 2.0 Hi-Speed Hub Controller

Chapter 1 Overview
USB 2.0 Hi-Speed Hub Controller
Datasheet
1.1
The SMSC USB251xB/xBi hub family is a group of low-power, configurable, MTT (multi transaction
translator) hub controller ICs. The hub provides downstream ports for embedded USB solutions and
is fully compliant with the USB 2.0 Specification [1]. Each of the SMSC hub controllers can attach to
an upstream port as a full-speed or full-/hi-speed hub. The hub can support low-speed, full-speed, and
hi-speed downstream devices when operating as a hi-speed hub.
All required resistors on the USB ports are integrated into the hub. This includes all series termination
resistors and all required pull-down and pull-up resistors on D+ and D- pins. The over-current sense
inputs for the downstream facing ports have internal pull-up resistors.
The USB251xB/xBi hub family includes programmable features, such as:
„ MultiTRAK^TM Technology: implements a dedicated Transaction Translator (TT) for each port.
Dedicated TTs help maintain consistent full-speed data throughput regardless of the number of
active downstream connections.
„ PortMap: provides flexible port mapping and disable sequences. The downstream ports of a
USB251xB/xBi hub can be reordered or disabled in any sequence to support multiple platform
designs with minimum effort. For any port that is disabled, the USB251xB/xBi hub controller
automatically reorders the remaining ports to match the USB host controller’s port numbering
scheme.
„ PortSwap: allows direct alignment of USB signals (D+/D-) to connectors to avoid uneven trace
length or crossing of the USB differential signals on the PCB.
„ PHYBoost: enables 4 programmable levels of USB signal drive strength in downstream port
transceivers. PHYBoost will also attempt to restore USB signal integrity.
Configurable Features
The SMSC USB251xB/xBi hub controller provides a default configuration that may be sufficient for
most applications. Strapping option pins (see Section 3.3.1 on page 22) provide additional features to
enhance the default configuration. When the hub is initialized in the default configuration, the following
features may be configured using the strapping options:
„ Downstream non-removable ports, where the hub will automatically report as a compound device
„ Downstream disabled ports
„ Enabling of battery charging option on individual ports
The USB251xB/xBi hub controllers can alternatively be configured by an external I²C EEPROM or a
microcontroller as an SMBus slave device. When the hub is configured by an I²C EEPROM or over
SMBus, the following configurable features are provided:
„ Support for compound devices on a port-by-port basis
„ Selectable over-current sensing and port power control on an individual or ganged basis to match
the circuit board component selection
„ Customizable vendor ID, product ID, and device ID
„ Configurable USB signal drive strength
„ Configurable USB differential pair pin location
„ Configurable delay time for filtering the over-current sense inputs
„ Configurable downstream port power-on time reported to the host
„ Indication of the maximum current that the hub consumes from the USB upstream port
Revision 2.2 (02-17-12)
8
DATASHEET
SMSC USB251xB/xBi